Earth's warming is getting a boost this year from an El Nino warming of the Pacific Ocean, Crouch added.

NOAA scientists think it's quite likely that 2015 will end up the hottest year on record, beating last year.

"I think, from my perspective, I would say [I'm] 99% certain that it's going to be the warmest year on record," NOAA climate scientist Jessica Blunden said during the press call.

"For it to change you're going to have to have a big change in the ocean temperature, which we've seen only trending warmer over time."

Earlier this week, preliminary data from NASA — along with information from the Japan Meteorological Administration — suggested that July was the warmest month on record. Now we know for sure.

The hottest July milestone comes as the U.S. government mobilizes military units to help respond to an escalating outbreak of wildfires throughout the West, much of which is tinderbox-dry and scorchingly hot.

While heat waves are synonymous with summer, the heat this year has set all-time records — which are rarely eclipsed to the extent that they have been in 2015.

Such temperature records have fallen on several continents. That makes the summer of 2015 stand out from others that featured record-smashing and deadly heat events, such as 2003, when an August heat wave killed more than 40,000 in Europe.

Extreme heat has been blamed for thousands of deaths from India to Egypt, into Europe and west to the Pacific Northwest cities of Seattle and Portland. Even Japan and Hong Kong have set all-time high temperature records and passed historical heat wave markers.

The heat waves began in June before the Indian Monsoon kicked into gear, as high temperatures well into the triple digits Fahrenheit hit India and Pakistan, killing more than 2,000 people.

Madrid, for example, set monthly high temperature records in both June and July, with a record high temperature on July 6 of 103.8 degrees Fahrenheit, or 39.9 degrees Celsius.

Germany broke its all-time heat record on July 5, when the temperature reached 104.5 degrees Fahrenheit, or 40.3 degrees Celsius, in Kitzingen, according to Germany's National Meteorological Service. The U.K. set an all-time July heat record when the temperature at London's Heathrow Airport reached 98.1 degrees Fahrenheit, or 36.7 degrees Celsius, on July 1, according to the Met Office.

Maastricht in the Netherlands, set a new national July heat record in July, when the temperature reached 100.8 degrees Fahrenheit, or 38.2 degrees Celsius, according to the Weather Channel.

Comparison between ocean height measurements from August 5, 1997 and August 5, 2015, from NASA. Ocean height is used as a proxy for water temperatures.

Image: NASA JPL

Published scientific research shows that manmade global warming is very likely playing an integral role in intensifying, and possibly also triggering, these extreme heat events.

A study published in April in the journal Nature Climate Change found that the probability of 1-in-1,000-day hot extremes over land is already about five times higher than it was in pre-industrial times, when global average surface temperatures were lower. To put it another way, the study found that about 75% of "those moderate hot extremes are attributable to warming."

The study, along with many others, found that the probability of hot extremes is likely to increase significantly as global warming continues.

World leaders will convene in Paris starting on November 30 to forge a new climate change agreement that would limit greenhouse gas emissions after the year 2020. So far, the amount of emissions cuts pledged by countries including the U.S., China, European Union and Brazil do not add up to enough to limit global warming below the agreed upon guardrail: 2 degrees Celsius, or 3.6 degrees Fahrenheit, above preindustrial levels by 2100.

If Earth continues on its current emissions path, it is already headed for warming of up to 9 degrees Fahrenheit by the end of the century — which few climate scientists argue would be anything other than catastrophic. A drastic rise in sea levels, heat waves, species extinctions and shifts in extreme weather events would result.

In other words, this July record could be viewed as a warning of what may be in store depending on decisions made very soon.

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